diff --git a/lib/compress.js b/lib/compress.js
index 469ee6e2..9400b864 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1413,9 +1413,9 @@ merge(Compressor.prototype, {
             }
             else if (exp instanceof AST_Dot && exp.property == "toString" && self.args.length == 0) {
                 return make_node(AST_Binary, self, {
-                    left: exp.expression,
+                    left: make_node(AST_String, self, { value: "" }),
                     operator: "+",
-                    right: make_node(AST_String, self, { value: "" })
+                    right: exp.expression
                 }).transform(compressor);
             }
         }